Oil based drilling mud (OBM) filtrate contamination monitoring (OCM) is one of the biggest challenges in downhole fluid analysis. Conventional systems and algorithms are not capable of providing adequate results for OBM contamination monitoring, particularly with focused sampling interface modules. Accurate and quantitative OBM contamination measurement is a key enabler of quality sampling and quality downhole fluid analysis (DFA). New algorithms are highly demanded for this purpose.
Conventional systems do not disclose or suggest any capability that gas/oil ratios may be used in oil based mud filtrate contamination monitoring quantitatively. Previous attempts at developing a relationship have failed as conventional fluid analyzers display a negative gas/oil ratio in Oil Based mud filtrate. This limits its use in quantifying Oil Based mud contamination. Extrapolating contamination free gas/oil ratios determined by asymptotic fitting methods does not work, especially for focused probes and/or new developed probes and packers.